Process for washing acid treated distillate



Feb- 3L 1953 c. w. STRATFORD PROCESS FOR WASHING ACID TREATED DISTILLTE Filed Feb. 25, 1950 2 SHEETS-SHEET l 1N VEN TOR. kaf/e5 #Va/co# 5V/afford Feb 3, 1953 c. w. STRATFORD 2,627,496

l PROCESS FOR WASHING ACID TREATED DISTILLATE Filed Feb. 25, 195o v 2 SHEETS- SHEET 2 Patented Feb. 3, 1953 PROCESS FOR WASHING ACID TREATED DISTILLATE Charles Walcott Stratford, Kansas City, Mo., as-

signor to Stratford Engineering Corporation, Kansas City, Mo., a corporation of Delaware Application February 25, 1950, Serial No. 146,378

3 Claims.

This invention relates to improvements in a process for washing acid treated distillates and refers more particularly to a process for removing salts of sulfonic bodies, ash or color-bearing constituents from lubricating oil distillates previously treated with acid.

The process is an improvement over that described in Patent 1,927,853 and an application Serial No. 95,702 led May 27, 1949, now Patent No. 2,585,874. As described in these prior cases,

the washing of the oil was conducted by water washing the distillate in one or more stages to remove objectionable constituents. With some oils purification suificient to meet specification requirements cannot be obtained by simple water washing methods. The use of steam, however, readily brings the oil, after acid treating and neutralization, to the desired specications with little difficulty.

An object of the invention, therefore, is to provide a method of washing lubricating oil distillates, which have been acid treated, with steam to remove ash, color bearing constituents and salts of sulfonic bodies.

Another object is to prevent loss of color of the oil which takes place in water washing methods heretofore used reducing the amount of acid dosage required to produce a specified color.

A further object is to eliminate emulsions frequently formed by conventional water washing and make the gravity separation of the oil from the washing fluids more rapid and complete.

Other objects and advantages will be apparent from the description which follows.

In the accompanying drawings which form a i part of the specification and are to be read in1 conjunction therewith and in which like reference numerals indicate like parts in the various views,

Fig. l is a schematic flow diagram of a portion of a treating system embodying the invention, Fig. 2 is a graph in which NPA color is charged against acid dosage pounds per barrel of charge.

the temperature of this medium is regulated by the outlet temperature of the oil dihflged IOm tactor I6 through pipe II.

lthe exchanger through pipe I3. To accomplish Y this regulation, connections of the control device I I are interposed in the discharge line I3 and operate valve I5 which regulates the amount of cooling or heating medium supplied to the exchanger. After being heated to the proper degree the oil is charged to a motor driven contacting device IB where it is intimately mixed with a neutralizer supplied to the contactor through pipe I'd. In this stage the sour oil and alkali are combined at relatively elevated temperatures and under sucient pressure to keep all components of the mixture in liquid phase after which the mixture is passed to heat exchanger I8. The temperature within this exchanger is similarly controlled as in exchanger I by a temperature control device I4. From heat exchanger I8 the oil and alkali mixture is passed through pipe 2G to a settler 2I where separation of the neutralizer from the oil is eiiected. The neutralizer is passed to drum 22 and the oil is removed through pipe 23 through which it is directed to a steam mixer 24. Neutralizer collected in the drum 22 is recycled through pipe 25 and by means of pump 26 is recirculated to the neutralizing con- A withdrawal line 27 controlled by valve 28 may be used to remove spent soda or other neutralizer from the system from time to time as desired. Fresh neutralizer is mixed in make-up tank 29 and is supplied to the system through pipe 36.

In some instances it may be necessary to carry a higher temperature in the neutralizing settler 2l than is employed in the preceding contacting step I6 for purposes of facilitating the gravity separation of the alkali solution from the oil.V l It is for this reason that the heat exchanger I8 is provided before the mixture enters the settler. Pressure on the settler is held suiiiciently high to prevent vaporization of water or oil. When neutralization is accomplished under conditions of elevated temperature and pressure the optimum strength of the neutralizing system in the case of caustic soda solution may vary between 2% and 30% on the dry base caustic soda.

In the rst stage steam wash mixer 24, steam is supplied through pipe 3i to be mixed with the oil f or the purpose of removing alkali salts of sulfonic bodies or color-bearing constituents. The eiliuent iiows through pipe 32 into heat exchanger 33 likewise regulated by temperature control device I4, as were the previous heat exchangers in the system. The temperature to which the oil-steam mixture is cooled in this heat exchanger must be such as required to insure complete condensation of the steam but as little below that temperature as practical to maintain, so that the condensed steam will readily settle in condensate settler 34 to which the oil is passed through pipe B5. The wash condensate Water is drawn oir continuously from the bottom of thesettler through pipe'i, while the oil is removed from the top through pipe 3l. It is contemplated that one or more steam washing stages may be required and in the drawings there" has been shown a two-stage. system. The sec:-A ond stage steam wash mixer is diagrammatically shown at 38 to which the oil is supplied through pipe 3l and steam is introduced tothe second' stage mixer through pipe m. From theisecond steam washing stage the oil and steam are passed through pipe 38h through heat `exchanger35i-reguing stage as well as the percentage yield of iinished` oil. The, process is particularly adapted to relatively heavy oils above 500 viscosity SSU at 100 F. The oil treated in the operations included within the tabulation was a distillate having a viscosityV of approximately 2200 Saybolt Seconds Universal at 100' F. originating from a napthenic base Texas-iCoastalcrude oil* 3-Stage 3 St Charge Steam Charge age Charge 3`Stage Treating Conditions Water v Water Stock. lirlzltii Stock, Washingl toch Washing Acid' Dosage, #/bbl. oil 0.0 6': 0 0.0 6. 0 0.0 16. 5 Acid Treating. Temp.. I". 175' 175 175 Total Steam, #/bbl; Oil. 365. None None. None None Total Water, #/bbl. Oil None None 4,200l None 4, 200 Product Inspection:

Gravity, A. P. O 210 20. 9 20.4v 2l. 20.5 21.3 Viscosity, SUV, at 100 F 2, 219 2, 064 2, 002 l, 866 2,184 1,853 Viscosity, SUV, at 210 F f 98. 6 96. 4 95. 4 92A 6 98.0 92.6 or, Nr 8+ 4% s+ 6 s+ 41/2 Carbon Residue 0.24 0.33 0.146 0. 55 0.144 0. 53 Neutralization No. 0. 04 0.03 0. 03' U. 04 0. 06 0. O4 Ash, percent l... Nil Nil il- 0.0i Nil .058 Ash Removal Per Washing Stage:

Caustic WashedOil 0. 550 lst StageAsh, percent.. 0. 190 2nd Stage Ash, Percent 01068 3rd Stage Ash, Percent...- 0.058 Yield Finished, Oil, Percent... 92.8

lated by'temperature.V control device I :i and thence through-r pipe 40 to a second condensate settler 4i. Asf` in the'v previous settlingstage thev condensed steam" is removedgthrough. the condensate drain 3'6 while the oil ispassed overhead' through pipe t2-itc: a dehydrating device: of any conventional type, but shown; diagrammaticall'y in the drawingH asfy a.flash .evaporator 0.3. A back pressure regulator diagrammatically shown. at ylli isinterposed.y in .thelline4`2 anda vacuumA is imposed on evaporator- 43' through pipe e5. The dry acid treated neutral oilliswithdrawn from the evaporator through pipe- 46.

l'orE best'A results. the washing stages 24 and 3l areV operated above 212?. .atwhich .temperatures the viscosity and surface` tension of the oil are loweredfaclitating good'lmixing; It is essential that thesettlers. 2l', Se. and M1 be operated entirelyI intheliquid' phase and' in. order to prevent, Vaporiza-tion. of'. water under the conditions of temperature which are desirable for goodsettling it' isznecessary to hold'a' back pressure on the systeminexcess of thavapor. pressure of water at theaopera'ting temperatures;

Thelquantityof' steam usedinthe washing steps 2li!A and 312 may vary between 10 pounds and 150 pounds per barrel of oil per washing stage. Normally' the: settling time required in both the neutralizationa settler andthesteam condensate settlers will be short but in some instances as much asl three hours may be required. Pilot plant operations show that sulfonate bodies, ash and some color-bearing constituents are not completely removed by hot water washing but are definitely removed fromthe acid treated oil when steam is employed in one'or more steam washing stages.

There is shown below a tabulation wherein a comparison `is made of the results between a threestage steam injection washing and two threei, fell off to. 92.8%.

On thevgraph shown in F-g.2 are plotted curves showing the effect of` water and steam washing. The elect of the water washing operation isv indicated in the-upper lineand the steam washing operation in the lower line. The dotted lines indicate the probable shape of the-curves in the unexplored region atvery 'low acidl dosages. These curves were developed from the-treatment of the same (2200) viscosity SSUfTexas distillate described above usingf98% sulfuric acid dosages according to the pounds perbarrel shown with the resultant NPA- colors. This curve clearly shows that it isl possible to get a given colorwith much less acid when utilizing steam washing than when using water washing'.

To produce a finished oil having: 4%,- NPA color; ash, nil;` neutral No. 0,-03 orv less; carbon residue 0.50 orless, it was,` found necessary from pilot plantoperatiomas shown bythe schedule, to use S-Stage steam injection` washing. The charging stock for each treatment, as indicated in the schedule, while substantially the same, differed slightly in respect to viscosity due. to' the fact that each ofthe three samples wastaken from a different tank of oil. All requirements of the nished oil'specicationy were met by washing with steam in three-stages when using 6 pounds of 98% sulfuric acid pery barrel and a 94% yield of product was obtained. To accomplish the same results when using three-stage waterwashing it was found, as shown in the tabulation, that it was necessary to use 161/2 pounds acid per barrel and even then ash specications were not met. The product yield also Tov show` the improvement of steaming there has been listeda three-stage water washing operation using only pounds of acid per barrel of oil resulting in. 6 NPA C0101- and 0.04 ashwhich propertiesdo not meet the necessary specications.

It will be seen from the above that there is a decided improvement and unexpected result obtained by substituting steam Washing in place of Water Washing. Why the improvement occurs is not definitely known but the results in so far as improvement of product, yield and removal of ash and carbon residue speak for themselves.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent thereto.

It will be understood that certain features and subcombinations are of utility and may be employed Without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

l. A process of neutralizing and finishing luf bricating oil preliminarily treated with acid, comprising the steps of contacting the acid treated oil with a neutralizing agent in amounts sufcient to neutralize the oil and separating the neutralizing agent from the oil, then contacting the oil in a closed system with steam and finally condensing the steam and separating the oil from the condensed steam.

2. A process of neutralizing and nishing lubricating oil preliminarily treated with acid,

comprising the steps of contacting the acidtreated oil With a neutralizing agent in amounts sufficient to neutralize the oil and separating the neutralizing agent from the oil, then contacting the oil with steam in a closed system in a plurality of successive stages and condensing the steam and separating the oil from the condensed steam after each steam contacting stage.

3. A process of neutralizing and nishing lubricating oil preliminarily treated with acid, comprising the steps of contacting the acidtreated oil with a neutralizing agent in amounts suicient to neutralize the oil and separating the neutralizing agent from the oil, then contacting the oil with steam in a closed system in a plurality of successive stages and cooling the oil after each steam contacting stage to remove moisture condensate and nally separating the remaining moisture from the oil by evaporation.

CHARLES WALCOTT STRATFORD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Nurnoer Name Date 1,761,328 Chappell June 3, 1930 1,816,872 Rial Aug. 4, 1931 2,361,455 Chechot Oct. 31, 1944 OTHER REFERENCES Koetschau: Z. Angew. Chem., 32, -6 (1919), C. A. 13, 2758-9 (1919). 

1. A PROCESS OF NEUTRALIZING AND FINISHING LUBRICATING OIL PRELIMINARILY TREATED WITH ACID, COMPRISING THE STEPS OF CONTACTING THE ACIDS TREATED OIL WITH A NEUTRALIZING AGENT IN AMOUNTS SUFFICIENT TO NEUTRALIZE THE OIL AND SEPARATING THE NEUTRALIZING AGENT FROM THE OIL,THEN CONTACTING THE OIL IN A CLOSED SYSTEM WITH STEAM AND FINALLY CONDENSING THE STEAM AND SEPARATING THE OIL FROM THE CONDENSED STEAM. 